1. Field of the Invention
The present invention generally relates to antennas for receiving broadcast signals such as television signals, and more specifically relates to television antennas for receiving digitally formatted broadcast signals.
2. Description of the Prior Art
Conventional indoor TV antenna systems generally include two separate antennas for respective VHF and UHF reception. The antenna for receiving the VHF bands employs a pair of telescopic elements forming a dipole with each of the elements having a maximum length of from 4 to 6 feet (1.5 to 2.5 m). The two elements usually are mounted to permit the elements to be spread apart to increase or shorten the dipole length and those elements are commonly referred to as “rabbit ears.” The indoor UHF antenna typically is a loop having a diameter of about 7½ inches (20 centimeters).
One problem associated with the conventional indoor antenna systems is that the physical dimension of the VHF dipole is undesirably long for the ordinary setting in a living room and that the length as well as the direction of the dipole elements may need to be adjusted depending upon the receiving channels. The second problem is that the performance of such conventional indoor VHF/UHF antennas changes in response to changes of the physical conditions around the antenna elements. For example, it is difficult for a user to make proper adjustment of the antennas since a human body coming into contact with an antenna changes the electro-magnetic conditions associated with the antenna elements. The third problem is that the conventional indoor antenna systems do not always provide a sufficient signal level for good reception.
U.S. Pat. No. 6,429,828, which issued on Aug. 6, 2002 to Prapan Paul Tinaphong, et al., the disclosure of which is incorporated herein by reference, describes an antenna system for receiving VHF/UHF broadcast signals which comprises a planar antenna and a tuner unit which includes a tuning arrangement. A gain controllable amplifier may be included in the tuner unit where necessary. The planar antenna includes a pair of antenna elements which are substantially identical in shape. These elements are located on the respective surfaces of a dielectric board. The tuning arrangement includes a plurality of matching networks for the respective plurality of bands of broadcast frequencies.
The antenna and antenna system described in the aforementioned Tinaphong, et al. patent work well for receiving analog television broadcast signals. Now, the inventors herein have improved the planar antenna described in the aforementioned Tinaphong, et al. patent to have even better reception characteristics, including the capability to receive digitally formatted broadcast television signals.
NTSC (National Television Standards Committee) broadcast signals were adopted by the United States in 1941 as the standardized television broadcasting and video format which is currently in use. The NTSC signals are analog signals. However, the NTSC analog format will be phased out on Jun. 12, 2009, and all TV broadcasting signals will be changed to an ATSC (Advanced Television Systems Committee) digital format. The ATSC standard for digital television has been adopted by the United States and several other countries.
As a result, the television receiver antenna will become a critical element for the new digital TV reception system in order to receive all new digital TV channels which will be mainly in the UHF (ultra high frequency) band, with some channels being in the upper VHF (very high frequency) band covering conventional TV channels 7 to 13. Without a good omni-directional TV antenna, consumers will not be able to receive all of the digital ATSC signals when the broadcast format change comes about. All conventional indoor or outdoor antennas will only receive the signals when the antenna is pointed in the direction of the TV broadcasting station; otherwise, the converter box or ATSC television will only show a blank screen on the television. With the analog NTSC broadcast signals, consumers still can see some pictures or snowy images when the antenna is not pointed into the right direction, and consumers can still rotate the antenna to the right direction by watching the picture quality change the display on the television. Digital televisions that receive ATSC signals will either display a picture or a blank or dark screen, and thus provide no indication that will alert consumers that they should rotate the antenna to achieve better channel reception in the same area.